If using fresh pumpkin, discard seeds. Scoop out flesh, using a large spoon, into a food processor. Process until smooth, about 1 minute. Measure out 3 cups, and transfer pumpkin to a large bowl (reserve any remaining for another use; if using canned pumpkin, add that to the bowl instead). Add brown sugar, cornstarch, salt, cinnamon, ginger, vanilla, nutmeg, remaining 6 eggs, and evaporated milk; whisk until combined.